Make signal handling work well across platforms

- Fix sigsuspend() on XNU
- Fix strsignal() on non-Linux
- Add unit tests for strsignal()
- Add unit tests for setitimer()
- Add unit tests for sigsuspend()
- Rewrite setitimer() for New Technology
- Rewrite nanosleep() for New Technology
- Polyfill SIGALRM on the New Technology
- select(0,0,0,0) on NT now calls pause()
- Remove some NTDLL calls that aren't needed
- Polyfill SA_NOCLDWAIT on the New Technology
- Polyfill SA_RESETHAND on the New Technology
- Polyfill sigprocmask() on the New Technology
- Polyfill SIGCHLD+SIG_IGN on the New Technology
- Polyfill SA_RESTART masking on the New Technology
- Deliver console signals from main thread on New Technology
- Document SA_RESTART behavior w/ @sarestartable / @norestart
- System call trace in MODE=dbg now prints inherited FDs and signal mask

libc/str/kstrsignal.S

@@ -0,0 +1,69 @@
+/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
+│vi: set et ft=asm ts=8 tw=8 fenc=utf-8                                     :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/macros.internal.h"
+
+	.macro	.e e s
+	.long	\e - kStrSignal
+	.long	1f - kStrSignal
+	.rodata.str1.1
+1:	.string	"\s"
+	.previous
+	.endm
+
+	.section .rodata
+	.align 4
+	.underrun
+kStrSignal:
+	.e	SIGHUP,"HUP"
+	.e	SIGINT,"INT"
+	.e	SIGQUIT,"QUIT"
+	.e	SIGILL,"ILL"
+	.e	SIGTRAP,"TRAP"
+	.e	SIGABRT,"ABRT"
+	.e	SIGBUS,"BUS"
+	.e	SIGFPE,"FPE"
+	.e	SIGKILL,"KILL"
+	.e	SIGUSR1,"USR1"
+	.e	SIGSEGV,"SEGV"
+	.e	SIGUSR2,"USR2"
+	.e	SIGPIPE,"PIPE"
+	.e	SIGALRM,"ALRM"
+	.e	SIGTERM,"TERM"
+	.e	SIGSTKFLT,"STKFLT"
+	.e	SIGCHLD,"CHLD"
+	.e	SIGCONT,"CONT"
+	.e	SIGSTOP,"STOP"
+	.e	SIGTSTP,"TSTP"
+	.e	SIGTTIN,"TTIN"
+	.e	SIGTTOU,"TTOU"
+	.e	SIGURG,"URG"
+	.e	SIGXCPU,"XCPU"
+	.e	SIGXFSZ,"XFSZ"
+	.e	SIGVTALRM,"VTALRM"
+	.e	SIGPROF,"PROF"
+	.e	SIGWINCH,"WINCH"
+	.e	SIGIO,"IO"
+	.e	SIGSYS,"SYS"
+	.e	SIGINFO,"INFO"
+	.e	SIGRTMAX,"RTMAX"
+	.e	SIGRTMIN,"RTMIN"
+	.e	SIGEMT,"EMT"
+	.long	0
+	.endobj	kStrSignal,globl,hidden
+	.overrun

libc/str/strsignal.c

@@ -20,28 +20,42 @@
 #include "libc/macros.internal.h"
 #include "libc/str/str.h"
 
-static const char kSig[4] = "SIG";
-static const char kUnknown[8] = "UNKNOWN";
+extern const struct { int x, s; } kStrSignal[];
 
-_Alignas(char) static const char kStrSignals[][8] = {
-    "EXIT",   "HUP",  "INT",    "QUIT", "ILL",   "TRAP", "ABRT", "BUS",
-    "FPE",    "KILL", "USR1",   "SEGV", "USR2",  "PIPE", "ALRM", "TERM",
-    "STKFLT", "CHLD", "CONT",   "STOP", "TSTP",  "TTIN", "TTOU", "URG",
-    "XCPU",   "XFSZ", "VTALRM", "PROF", "WINCH", "IO",   "PWR",  "SYS",
-};
-
-static char g_strsignal[4 + 8];
+static char g_strsignal[12];
 
 /**
- * Returns name associated with signal code.
+ * Returns string describing signal code.
+ *
+ * This returns SIGUNKNOWN for 0 which is the empty value. Textual names
+ * should be available for signals 1 through 32. Signals in the range 33
+ * and 128 are returned as a `SIG%03d` string. Everything else is SIGWUT
+ *
+ * @param sig is signal number which should be in range 1 through 128
+ * @return pointer to static memory that mutates on subsequent calls
  * @see sigaction()
  */
 char *strsignal(int sig) {
-  if (0 <= sig && sig < ARRAYLEN(kStrSignals)) {
-    memcpy(g_strsignal, kSig, 4);
-    memcpy(&g_strsignal[3], kStrSignals[sig], 8);
+  int i;
+  strcpy(g_strsignal, "SIG");
+  if (sig) {
+    for (i = 0; kStrSignal[i].x; ++i) {
+      if (sig == *(const int *)((uintptr_t)kStrSignal + kStrSignal[i].x)) {
+        strcpy(g_strsignal + 3,
+               (const char *)((uintptr_t)kStrSignal + kStrSignal[i].s));
+        return g_strsignal;
+      }
+    }
+  }
+  if (!sig) {
+    strcpy(g_strsignal + 3, "UNKNOWN");
+  } else if (1 <= sig && sig <= 128) {
+    g_strsignal[3] = '0' + sig / 100;
+    g_strsignal[4] = '0' + sig / 10 % 10;
+    g_strsignal[5] = '0' + sig % 10;
+    g_strsignal[6] = 0;
   } else {
-    memcpy(g_strsignal, &kUnknown, 8);
+    strcpy(g_strsignal + 3, "WUT");
   }
   return g_strsignal;
 }